Ford Focus Problem in Cool Weather

I'd be looking at temp sensors too that work with your fuel injection. if the computer "thinks" the engine is running cool it will feed a map to the injectors that will give the exact result you describe, I'd bypass the dealer and go to a fuel injection guy

Thanks Fredisky: That was my thoughts based on the dealer diagnosis not revealing any issues. Of course I have to go easy on the monetary side and I appreciate the suggestion. So far the great Ford Motor Company cannot even tell me how many sensors there are that feed temp info to the ecu. or fuel computer..

I'd start here...

Thanks I have the sensor and will go to the dealer asap. My dash gage is about two needles below 50% and on real hot days it is straight up. The dealer wants $ 200.00 to drain the coolant and change the unit so I bite the bullet and get on with it. Hope this works only problem even the dealer cannot or will not tell me how many sensors there are for transmitting this info. Are all diagnostic tools of equal value or is there a brand that has an outstanding reputation? $ 75.00 to plug in a tool and tell me no problems really does not register as money well spent. Then again I have limited options.

Fredski,

I agree, that sounds the most likely suspect from the symptoms, likewise it could be a bad connection to the temp sensor, adding extra resistance to the circuit ..... dirt, grease, corrosion, loose connection .... any or all of the above in the sensor circuit could also be the culprit.

Another source of advice/help could be your local Ford owners club, they often have a wealth of experience and are willing to share it.

A poor connection can always be a problem, but why is the problem not there when above 80. I once had an early Chrysler Lean Burn system that did not like to run when warmed up. Customer only drove about six blocks to work, so it worked well most of the week. Turns out that the air cleaner mounted ECM was temp sensitive. Till she could afford one, we sprayed the windshield washer on it when it would start to run crappy. It survived three weeks till she got a new one. So temp can affect many things, but for my first guess, I would check the air temp first.

Bob,

You could be right. My thinking was that some extra resistance in the circuit would make it appear cold for longer, perhaps until it is really quite warm, as only occurs on a hot day. This could occur on any temp sensor air, engine, water, oil, exhaust, etc. Likewise a Temp sensor could be failing progressively.

Likewise a dodgy Temp switch could be the culprit .....

If you can get the test specs for the different sensors you can check their resistance when they are cold and when they are at normal operating temperature....

On the other hand a build up of 'gunk' in the cooling system could be insulating a water temp sensor from accurately reading the water temp .... if that was the case some cooling system cleaner and a back flush followed by some new coolant may help....

Many possibilities...

this might helphttp://www.carsdirect.com/car-repair/how-to-tell-if-you-have-a-faulty-coolant-temperature-sensor

41 MPimpG sounds very good. Do you do long runs generally, or is it just careful driving? I have a Focus 2.0l Zetec (turbo), and I average about 30, but I mostly do ~10-mile runs. It's a lot better over ~50 miles.

Thanks to all the input, the 41 MPG is imperial gallon which we in Canada were on before we went metric and my fuel mileage slide calculator give me both MPG and Liters per 100 KM. I think we have narrowed it down to the coolant temperature unit ( sort of) as even on the coldest days cabin heat is great. Also I changed the IAT Intake air sensor which is also the MAP unit mainly because it was mentioned in all my discussions with automotive persons and easy for me to change and relatively inexpensive. Last night -20 my battery failed ( 5 yrs) and it did show signs of fatigue but now has been replaced so I will fill up today and check the idle and mileage again. I have the sensor on hand or one of them so it will be changed very soon.. Thanks again..& happy motoring.

Even a failing battery can possibly cause strange errors.....so check and see if anything now works better....long shot but cheap as you had to buy the battery anyway!!

Based on how the car is running in -15 I suspect things are improving next tank will give some indication. When driving home last night and it feld quite different and better and my thoughts went back to my 1990 Ford F250 Diesel. it had two batteries and when one started to fail my mileage dropped and came back when I installed the new battery. Dealer was flabergasted for a reason why a mechanical diesel would run better with batteries in better condition. This truck did not even have an electric fuel pump. My car problem started over 2 years ago yet it started every time and the only boost it needed was the time I went on 2 week vacation and I left the dash cam on. That was also winter time..

I forgot...... this can happen without any codes coming up.

The Crank Position Sensor can cause this, and it doesn't throw codes. You will "save" a lot of money, by getting from our far east friends. However, it may not work, it might not even fit. Guess how I know that?

Thanks this is the kind of info I need and it fits the experiences. GA from me..

The TSB says to replace the throttle body. The throttle position sensor goes bad in it and it is a non-servicable part.

I will consider but I fail to see the temperature connection. This car has the electronic throttle which I absolutely hate but most cars have the same. Driving a car and asking a third party to perform part of the driving function is foolish and dangerous, just ask Toyota drivers.. sorry they are 6 feet under.

I just mentioned it because it's the only sensor Integral to the Throttle body that I'm aware of. There may be others including temp sensors integrated into it as well.

Thanks I see you were very familiar to the realm of cold for some time. Now yo can play in deep snow.

For $10 US funds you can get a pdf download from ebay.

Focus 2011 shop manual

If you want a paper manual $100

2011 Focus paper manual

Outside of that I think Fredski pointing at sensors is the issue. But real cold outdoor conditions can cause sudden increase in fuel consumption. Any chance your fuel didn't go from no ethanol to 15%? Those folks that have the E85 vehicles learned it didn't save them money with subsidized cheap fuel.

This started in warm weather and over two years that has been consistent. Only if temp outside is over 80 does it run as intended. I am convinced that it is temp related and of course being in Canada we are aware of cold temp fuel usage. For anyone reading this the MPG is in Imperial gallons, but the Liters per 100 KM is universal. I have not purchased a manual because of my age 70 and leaning over a lunchbox working on something with no access if your hands are over 1 inch wide is a serious issue. Thanks again..

Purchasing a factory shop manual and reading it cover to cover will put you ahead of 90% of the factory trained technicians who are taught to pull codes, replace parts, and never to do anything that is not in a TSB.

Your automobile is now a rolling computer with more processing power and sensors than the early NASA space missions. The manual will have a description of how each subsystem and its sensors interact, but it will never cover the myriad of combinations of faults between subsystems, only your mind and your direct knowledge of what's going on can make that happen.

If you drive to a good independent mechanic and tell him what you've discovered he'll appreciate the fact that you saved him a lot of time (and he'll be less likely to try and BS you). The shop manual is the Secret Decoder Ring for talking to any mechanic, get one.

Yes, some vehicles have two separate sensors with one reporting to the instrument display and the other reporting to the ECM for fuel-to-air ratio control.

Because the issue appears to be temperature related it could be due to a loose and/or dirty sensor connection.

I suggest you check each and every engine sensor connector by disconnecting them one at a time, cleaning the contacts then spray with WD40 or use a good quality anti-oxidant that is rated for 12VDC usage and reconnect.

I would also check the MAS (Mass Air Flow) sensor for correct impedance values at a known temperature.

I would pay careful attention to the engine air bypass valve operation as it can cause the same symptoms.

Clymer and other aftermarket service book providers usually have the resistance values listed in their manuals along with the procedure for checking sensor operation.

Recently hear a "Car Talk" program on US-PBS radio about a similar problem and they (the engineers/mechanics) said that the problem could be a combination of faulty thermostat in the engine outlet feeding the radiator- failed "OPEN" so the engine was not getting to proper temperature during cold weather- warm enough to heat the car but NOT warm enough to feed "right " signals to electronics, so engine was staying in the "warm-up" (high choke, high idle, lots of gas use) mode. Warmer weather reduced ability of radiator to throw away enough heat so everything worked "right".

It is a cheap, easy-to-change part so worth a try.

Other possibility was faulty sensors, but this usually can be checked by looking at the engine coolant temperature gauge- if car is equipped with one- which would be showing "cool" conditions at all times.

I am with you on this, changing the thermostat is an easy and relatively easy start.

The whole failure description reeks of thermostat!!!

Suggest you read the OP: "Several mechanics suggested the EGR valve due to rough idle so it was changed with no success so I ordered a thermostat and had it changed with no change."

Ah! I missed that bit, thanks for the Heads Up!!

OK, I am not as familiar with the systems on Fords, as GM, but they all need the same information, so here goes.

A computer sensor usually needs a feedback to the computer. That is a 5 volt signal from the computer, a ground signal, and a variable signal to determine the temperature. Instrument gauges that measure temperature are powered at the dash gauge, and only need a variable ground signal at the engine water jacket. So, check the sensors that are installed in your water jacket. If only one wire, likely an instrument sender. If three wires, likely computer sensor.

Another hint. For years, Ford used the same temp sensor for air temp, and water temp. So the connectors would be the same. The air temp sensor is easier to find. It is in the air ductwork leading to the engine. Find it, then look for a similar one in the water jacket.

It is my belief that either of the two temperature sensors feeding the computer can cause an engine to think the temperature is colder than it is, and cause a richer idle mixture than required.

Do you have a GOOD auto parts close to you? They are a wealth of knowledge. First off, once you have located the AIR temp sensor, find out from the parts store the resistance that should be read on it at specific temperatures. Armed with this info, test it in water at freezing point, and at the boiling point. These temps will be free from thermometer accuracy issues. If the air temp sensor checks out within a few percent of correct, Go back to the parts store, and find a pipe plug the same size as the coolant temp sensor. With a cold engine, remove the sensor, and quickly screw in the pipe plug. Coolant loss is less than an ounce. (unless you drop the pipe plug). Then the same water temp test.

These tests should cost next to nothing, be able to be performed by most handy people with simple tools (OK, you need a digital volt, ohm meter, but they are cheap for no name models).

My guess is the air temp sensor. Why, because the coolant sensor is bathed in warm water which should remain consistent once the heater starts to work.

If all this fails, a competent mechanic with a decent code reader can read the temperature signal being sent to the computer in real time. That information will show weather or not the temp sensors are sending correct information. Screw the stealer dealer. If they wanted to help you, they would have told you this, or better yet, checked the readings from the temp sensors when you were there. Good luck. Stay here and let us help. Bob.

I also missed the "thermostat" comment but it seems like some type of sensor issue is still the most likely culprit.

Hope all improves very soon.

You did not say how many miles are on the vehicle. Have you checked the air filter/fuel filter, and any emissions filters? How about vacuum lines? Vacuum controls a lot of emissions components, having an effect on idle speed.

All these items have been inspected and declared ok.. KM are 120,000 or about 70,000 miles.

This is my suggestion:

Get a code reader. Go to inova dot com / they make good quality code readers. What you need is a code reader that does 4 things:

1. Tells you active codes ( some codes can be active and your check engine light will not be on).

2. Tells you stored codes ( sometimes you will have several code's stored at the same time having an active code and you need to address each code separately).

3. Gives you live data ( this way you can see when the fault occurs and under what conditions, e.g. engine cool, engine hot, part throttle, wide open throttle etc)

4. Allows you to test each sensor circuit separately ( 02 sensor 1, 02 sensor 2, IAT sensor, cmp sensor, etc).

Plan on spending at least $300.00

Don't waste your money on a Chilton or clymer book if your going to do serious diagnostics, Chilton and clymer books are for hobbyist's, not for wrench turners.

Contact Faxon auto literature in riverside, Calif. The company is owned by Ed Faxon, he has millions of factory shop manuals, he can probably get you a used factory manual set. This can save a huge chunk of change over what the ford dealer will charge.

Thanks very much I will check it out.. It is quite obvious to me the many code readers are lacking in function..

It is my personal opinion only, that the after market code readers do not fully decode the data often available. Only an original Ford analyser unit (in your case) will give the fine detail I believe.

Were you by Ford, or another workshop? You said "Ford Dealer" if I remember correctly, but there are Dealers and Dealers. If not directly by Ford, you may save yourself a lot of time by getting them to give you a full readout before going further....

Or try another Ford Dealer.

The above was true less than 10 years ago with some dealers, but as to whether its still true or not I cannot say.

The data is presented in several layers, all layers need to be fully decoded. Also, some "Dealers" do not hire intelligent mechanics for computer work......here at Dealerships they usually have a single person/department, who does all the Computer work, who hardly even gets his hands dirty!! Specialists!

Keep in mind that the ECM does not post or record an error code unless the sensor(s) feedback value is not within range.

Example: If the temperature sensor operating range limits are -50F to 300F and the engine coolant is 180F but the sensor is reporting a 30F value the engine will stay in the "cold start/run" mode and run very rich causing the engine to operate very roughly.

Since the reported sensor value is within normal sensor range the ECM will not post or record an error code.

This is why physical testing of the sensors is critical when experiencing the type of issues you are having.

This is also why it is critical to only replace sensors with devices that meet and comply with all OEM specifications without any deviation..

If you have access to a portable hand-held laser temperature sensing device it is possible to start the engine and after it has reached operating temperature (usually 200 - 210F) verify the temperature with the device then disconnect each temperature sensor and using a digital VOM check the sensor's resistance value against the test chart value. If no test chart/table is available and you know the resistance range as well as the sensor temperature range (usually stamped on the sensor or available from the parts supplier) it is a simple task to divide the resistance range by the temperature range to obtain the needed resistance value for a given temperature.

It is necessary to check the sensor(s) throughout the rated temperature range as the sensor can have a fault that only occurs at a specific temperature.

Some analyzers are capable of displaying each individual sensor value however in order to identify the issue you must compare the actual measured engine temperature against the value being reported to the ECM.

Hope this helps as I have fought this same issue with more than one of my family member's vehicles and it is a time consuming task that many dealerships and repair shops cannot or will not solve.

Assuming the new thermostat is not defective, it probably is not a coolant temperature problem.

Earlier post about running in warm up mode sounds like it's on track, but I suspect the ECM would monitor coolant temp for that.

A bad air fuel mix would create these symptoms, but for it to vary based on ambient temperature, it probably is caused by a bad air intake temperature sensor or a bad mass air flow sensor. I couldn't follow all the posts, but I think you wrote that you changed the AIT sensor. If that doesn't help, check the air flow sensor, not sure what Ford calls it. Also don't know how the air flow sensor works, but I think I remember one I looked at on a Chevy was basically a hot wire flow meter, based on heat lost from a heated element due to air movement - can be very badly much affected by ambient temperature.

Chevy has a MAP sensor, Manifold Air Pressure. I wouldn't expect it to be temperature sensitive, but it could be defective in a way that is affected by ambient air temp somehow. Less likeley to be an issue I think.

Thanks I have changed most of these parts and even cleaned the wire according to instructions with an electrical contact cleaner. I will visit the dealer parts dept and see if they can name the temperature sensors. It does seem a tad better with the new battery then again we are in deep winter with - 10 to- 20 C

Later posts seem to indicate that this has already been cleaned.....

You make a good point as these mass air flow hot wire sensors, can get very dirty (badly fitted or wrong sized, badly made air filter, leaks).

The dirt insulates the wire and gives a wrong reading about how much air is passing through the filter. Usually it thinks too little air is passing and it reduces the amounts of fuel being injected.

There are here in Germany cleaning kits to get the wires clean and also replacement units that only replace the part with the wires.....a cost saving over the whole unit.

I have had over the years several VW diesel engines where this has had to be replaced, the symptoms are possibly variable, but with VW Diesels it was an almost complete lack of power for my cars...

I was towing a heavy trailer once in the Italian mountains, that took off a big chunk of clutch plate!!!

I have not had it happen on a petrol/gas engine personally, so I do not know what the effects are. But it is an easy part to check out visually.

BY THE WAY, IT DOES NOT POST CODES AS THE ECM DOES NOT KNOW THAT IT IS DIRTY!!! At least on VW Diesels it posts no codes I should say....

That is a possible source of the problems I feel.

This thing about posting codes seems to be an area of contention. This is why you need a code reader that shows live data, then you can connect that to your lap top and record a map of a sensor(s) function(s).

The reason you need the factory service manual is because everything is a guess unless you know the actual range ( not some guess from 50 to 300 degrees ) of a specific component or subsystem.

Several things not aforementioned can cause driveability issues e.g. , fuel tank, vapor recovery and venting, transmission sensors and control solenoids, body control module, climate control module etc.

Including the wires and connectors connected to everything. On modern cars resistance values are a critical area, a dirty connector or a wire that even has a pin hole break can change resistance values.

A big part of diagnosing a vehicle is doing a performance check before and after a repair and following a diagnostic flow chart.

The most common mistake people make in repairing their cars is replacing one part then another part then another part in the hope that maybe they will get lucky and solve the issue.

In the mean time their bank account gets smaller in direct proportion to their temperment getting hotter.

GA

Very true I find!!

You have a lot of engine heat loss on colder days. Oh, its normal.

You could check Heat loss on engine = U x (Te - Tc/h) x Area

Where:

U- Heat Transfer Coefficient

Tc/h - Ambient Temperature at cold days or hot days

Te - engine Temperature

Area - estimate lateral area of engine volume (you could use rectangular cube engine)

Heat loss on hot days = U x (200⁰C-20⁰) x Area; Heat Loss on colder days = U x (200⁰ C- 5⁰C) x Area

Getting the ratio of Heat transfer of engine at cold and hot days would be (U & Area cancel out)

Heat Loss Ratio (Cold/Hot) = 195⁰C/180⁰C = 1.083 or about 8.3% increase on your fuel consumption.

Plus unaccounted fuel loss from heating your car cabin at colder days.

Obviously on colder days, you have greater difference in temperature between and ambient and there goes the extra energy of your fuel.

Even theoretically, combustion efficiency is increased in colder days but the main thing is ΔT.

Good explanation. But why don't all of the other cars in Canada and Alaska have this problem?

I thought about, is there summer on those places?

Yes, there is a summer, but, summer is a relative thing. Summer in the most northern (and southern ) climates might not be above 60F. degrees. Lyn's summer is ,, well very very hot.

LOL!